Two-dimensional PIC–MCC simulations of a capacitively coupled radio frequency discharge in methane

Two-dimensional capacitively coupled radio frequency discharge in methane is simulated by PIC-MCC method. The results were obtained in pressure range 50-300 mTorr and voltage range 40-180 V for discharge frequency 13.56 MHz. The electron energy and electron--methane reaction rates spatial distributions show existence of two regimes of discharge glow: a) with active sheaths, when electrons are hot in electrode sheaths and cold in the middle of discharge so the electron-neutral reactions strongly dominate in sheaths regions; b) with volume domination, when the electron energy is more uniform and the reactions take place in all discharge volume. The second regime is usually observed for low discharge voltages, and turns to the first one with voltage increasing. Besides, simulation of chemical reactions in methane plasma was also fulfilled to find the gas mixture composition in discharge volume. The results are in agreement with the known experimental data.